DPF Regen Effectiveness

[killerbee]

Keep your post injections in... If you kill them it will definately reduce your time between regens..

As a test, drop back to 2 injections.. Drive 20 miles and you're catalyst will be full.. Then turn on the handy dandy scan tool. You can watch soot mass in the DPF fall rather quickly with a 100% clogged filter if you go back to 5 injections.


I've got some clean 425rwhp tunes running out there with no issues. What problems were you having in particular?

I figured as much. I have a learning curve now, and figure that this thread might serve to help others not make the same mistakes, but also serve as a tech thread on DPF theory. We'd all like for regens to take as little fuel as possible.

BTW, what is the table number for the number of injection events? I must be losing it, I can't seem to find it now.

[killerbee]

Of you testing on her LMM ? Are you talking to me or Ross ? Ross


My theories on efficient combustion would point someone to use more fuel pressure instead of pulse width, increasing timing for more CP etc..

My experience with these trucks shows that by reducing the torque limiting will gain plenty of power without increasing the pulsewidth much if any.

One of my questions is about regen fuel pressure. Wondering if there are sep tables for regen process.

It also seems that an accurate oxygen algorithm (boost dependent) is an important part of the reaction equation. This and other dpf theory parts, require at least I ask some of these questions. It is not unreasonable, with the state of the truck changing every 300 miles, with all new parameters.

[Brayden]

B1021.. It's a limiter table by voltage and RPM. You can use it to your advantage to shape your number of pulses by RPM, which is not ideal, but works very well for a DPF'less truck.. Set it to 2 across the board except for low voltages.

[killerbee]

Thanks.

I had set most values to 3 (don't know why). I have used 2 with the LBZ without issue. Of course I think it only ever has 2 pulses, LOL.

So this leads to 2 questions

what does voltage actually represent. Never have gotten a straight answer to this.
What is pulse 5?... 4?... 3?... 2?

Is there 2 post pulses during regen?

Trying to log all these channels is going to pose a real challenge, on top of the other required data.

[Brayden]

LBZ only runs 2 injection events.

Of the 5 events You have:

Pilot Injection 1
Pilot Injection 2
Main Injection 1
Post Injection 1
Post Injection 2

If you drop back to 4 it should kill Post2
If you drop back to 3 it kills Pilot1 and Post 2
If you drop back to 2 it kills Pilot 1 and both Post 1 & 2
And that just leaves 1 event left and that is non piloted main injection

Running only 3 was reducing one of your post injections and hindering the systems ability to create sufficient late cycle heat required for efficient DPF operation.

[killerbee]

I was thinking that 3 eliminated both post events. Was that a bad assumption of mine?

[Brayden]

Voltage plays a very important role in an electronic injection system

Injection speed is dependent on voltage. If voltage drops too low, injection accuracy is compromised. That lookup table gives the ecm a threshold to abort injections if the voltage is too low to support them.

[Brayden]

From what I've read, it cuts from both ends, knocking off one post, then one pilot, etc etc.

[Brayden]

Do an experiment over an average drive cycle with 5 events, 4 events, then 3

[killerbee]

Voltage plays a very important role in an electronic injection system

Injection speed is dependent on voltage. If voltage drops too low, injection accuracy is compromised. That lookup table gives the ecm a threshold to abort injections if the voltage is too low to support them.

that helps. Thank you again.

Note that post 2, has no qty table associated with it. I assume it can't be adjusted?

Also, FWIW, pilot 2 shows 1mm3 for all cells (factory tune), yet in my logs, I have not seen any pilot 2.